# ENGEL e vs STL Simple Viewer

The clearest difference is in-app purchases: ENGEL e at none against STL Simple Viewer's 4. ENGEL e also leads on ads (none vs shown) and update cadence (every 4 months vs every 20 months). On price, review sentiment and device support there is nothing between them.

Both are free to download. STL Simple Viewer sells 4 in-app purchases, starting at $0.99 per 7 days. ENGEL e asks for nothing beyond the download.

ENGEL e ships an update every 4 months, STL Simple Viewer every 20 months. The most recent releases landed on July 3, 2026 and September 23, 2026 respectively.

## The numbers

| Metric | ENGEL e | STL Simple Viewer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.3 (866 ratings)](https://appshunter.io/ios/app/stl-simple-viewer/id1493598400/reviews)** |
| Number of ratings | — | **866** |
| Positive reviews | **25.0% of reviews** | 17.2% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 4 months** | Every 20 months |
| Monetization | **Free** | Free with in-app purchases |
| Size | 29 MB | 19 MB |
| Requires iOS | **13.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | +4 |
| Developer | [ENGEL AUSTRIA GmbH](https://appshunter.io/developer/687631542) | [Victor Bovio](https://appshunter.io/developer/327627515) |

## What reviewers say

### ENGEL e

[App page](https://appshunter.io/ios/app/engel-e-calc/id687631539)

This tool simplifies complex calculations for injection molders, including stroke volume, clamping force, cooling time, and screw speed. Get accurate results quickly and clearly displayed on a single page, eliminating the need for tedious manual computations.

**Highlights:** Calculate stroke volume, Determine clamping force, Estimate cooling time, Calculate screw speed, Clear, structured results display, Quick calculations

**Features:** macOS Compatibility

**In-app purchases:** none


### STL Simple Viewer

[App page](https://appshunter.io/ios/app/stl-simple-viewer/id1493598400)

Easily view and interact with 3D STL CAD models. Supports various file types and offers advanced rendering options for detailed analysis. Get model information and explore interiors with clipping planes.

**Highlights:** View ASCII and Binary STL files, Load STL from ZIP, Rotate, pan, and zoom, Orthogonal and Perspective modes, Model info (triangle count, bounding box), Rendering options (faces, edges, transparency), Clipping plane for interiors

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro version (1 week plan) | $0.99 | per 7 days |
| Pro version (1 month plan) | $1.99 | per month |
| Remove Ads | $2.99 | one-time |
| Export to OBJ, DAE, DXF, PLY | $3.99 | one-time |

**What reviewers like**

- 🚀 Simple and intuitive viewer
- 👍 Useful viewing options
- 💡 Supports multiple file formats

**What reviewers complain about**

- 🐛 Frequent crashes
- 🔋 High battery consumption
- 🚨 Excessive and intrusive ads
- 🔍 Limited functionality for larger files

**Reported bugs**

- App crashes when opening larger STL files
- Inability to open some file formats
- Ads continue to appear even after paying for ad removal

**Requested features**

- Add ability to save color/lighting settings
- Improve stability and reduce crashes
- Provide an ad-free paid version


## Frequently asked questions

### Is ENGEL e free?

ENGEL e is free to download, with no in-app purchases.

### Is STL Simple Viewer free?

STL Simple Viewer is free to download, with in-app purchases available.

### Do ENGEL e or STL Simple Viewer have ads?

STL Simple Viewer shows ads; ENGEL e does not.

### Which is updated more often, ENGEL e or STL Simple Viewer?

ENGEL e ships an update every 4 months, and STL Simple Viewer every 20 months. Most recently, ENGEL e was updated on July 3, 2026 and STL Simple Viewer on September 23, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*